From e.g. EP-Al-O 005 129 sulphoxides of the benzimidazole type with the general formula I ##STR4## in which R.sup.1 and R.sup.2 are the same or different and are hydrogen, alkyl, halogen, methoxycarbonyl, ethoxycarbonyl, alkoxy, or alkanoyl in any position, R.sup.6 is hydrogen, methyl or ethyl, R.sup.3, R.sup.4 and R.sup.5 are the same or different and are each hydrogen, methyl, methoxy, ethoxy, methoxyethoxy or ethoxyethoxy, whereby R.sup.3, R.sup.4 and R.sup.5 are not all hydrogen, and whereby when two of R.sup.3, R.sup.4 and R.sup.5 are hydrogen, the third of R.sup.3, R.sup.4 and R.sup.5 is not methyl, as well as pharmaceutically acceptable salts thereof are known. The compounds with the general formula I can be used in the treatment of gastrointestinal diseases.
The compounds are known to inhibit gastric acid secretion and have also a gastric cytoprotective effect. Because of their antisecretory effect they may be used in the treatment of peptic ulcer.
The antisecretory activity of the substituted benzimidazoles with the general formula I has been found to be mediated by inhibition of the gastric H.sup.+,K.sup.+ -ATPase, the enzyme responsible for the pumping of protons into the stomach. This enzyme is localized in the parietal cells in the gastric mucosa.
The in vivo inhibiting effect of the compounds with the general formula I is not, however, exerted by the compounds as such but by one or more degradation products.